The present invention generally relates to medical devices and methods for reducing intraocular pressure in the eye of mammals. More particularly, the present invention relates to the treatment of glaucoma via the use of a bent surgical device to surgically create a channel thereby permitting aqueous humor to flow out of the anterior chamber into the suprachoroidal space.
The human eye is a specialized sensory organ capable of light reception and able to receive visual images. The trabecular meshwork serves as a drainage channel and is located in anterior chamber angle formed between the iris and the cornea. The trabecular meshwork maintains a balanced pressure in the anterior chamber of the eye by draining aqueous humor from the anterior chamber.
Glaucoma is the second leading cause of blindness worldwide (Quigley H A and A T Broman, BR J OPHTHALMOL 90(3): 262-267 (2006)). Glaucoma is a group of eye diseases encompassing a broad spectrum of clinical presentations, etiologies, and treatment modalities. Glaucoma causes pathological changes in the optic nerve, visible on the optic disk, and it causes corresponding visual field loss, resulting in blindness if untreated. Lowering intraocular pressure is a major treatment goal in glaucoma.
In glaucomas associated with an elevation in eye pressure (intraocular hypertension), the source of resistance to outflow is mainly in the trabecular meshwork. The tissue of the trabecular meshwork allows the aqueous humor to enter Schlemm's canal, which then empties into aqueous collector channels in the posterior wall of Schlemm's canal and then into aqueous veins, which form the episcleral venous system. Aqueous humor is a transparent liquid that fills the region between the cornea, at the front of the eye, and the lens. The aqueous humor is continuously secreted by the ciliary body around the lens, so there is a constant flow of aqueous humor from the ciliary body to the eye's front chamber. The eye's pressure is determined by a balance between the production of aqueous humor and its exit through the trabecular meshwork (major route) or uveal scleral outflow (minor route). The trabecular meshwork is located between the outer rim of the iris and the back of the cornea, in the anterior chamber angle. The portion of the trabecular meshwork adjacent to Schlemm's canal (the juxtacanilicular meshwork) causes most of the resistance to aqueous outflow.
Glaucoma is grossly classified into two categories: closed-angle glaucoma, also known as angle closure glaucoma, and open-angle glaucoma. Closed-angle glaucoma is caused by closure of the anterior chamber angle by contact between the iris and the inner surface of the trabecular meshwork. Closure of this anatomical angle prevents normal drainage of aqueous humor from the anterior chamber of the eye. Open-angle glaucoma is any glaucoma in which the angle of the anterior chamber remains open, but the exit of aqueous through the trabecular meshwork is diminished. The exact cause for diminished filtration is unknown for most cases of open-angle glaucoma. Primary open-angle glaucoma is the most common of the glaucomas, and it is often asymptomatic in the early to moderately advanced stage. Patients may suffer substantial, irreversible vision loss prior to diagnosis and treatment. However, there are secondary open-angle glaucomas which may include edema or swelling of the trabecular spaces (e.g., from corticosteroid use), abnormal pigment dispersion, pseudo-exfoliation glaucoma, or diseases such as hyperthyroidism that produce vascular congestion. Glaucoma may also be referred to as “refractory” or “complicated,” both of which describe glaucoma that does not respond to typical drugs and treatments.
All current therapies for glaucoma are directed at decreasing intraocular pressure. Medical therapy includes topical ophthalmic drops or oral medications that reduce the production or increase the outflow of aqueous humor. However, these drug therapies for glaucoma are sometimes associated with significant side effects, such as headache, blurred vision, allergic reactions, death from cardiopulmonary complications, and potential interactions with other drugs. When drug therapy fails, surgical therapy is used. Surgical therapy for open-angle glaucoma consists of laser trabeculoplasty, trabeculectomy, and implantation of aqueous shunts after failure of trabeculectomy or if trabeculectomy is unlikely to succeed. U.S. Pat. No. 6,666,841 to Gharib et al. describes a trabecular shunt and a method for treating glaucoma comprising placing a trabecular shunt thorough diseased trabecular meshwork. U.S. Pat. No. 6,726,664 to Yaron et al. describes an implant having a tube for permitting fluid flow and delivery device for implanting the implant. U.S. Pat. No. 7,670,310 to Yaron et al. describes an implant and delivery device for implanting the implant in the eye. U.S. Pat. No. 5,342,370 to Simon et al. and related U.S. Pat. No. 5,676,679 to Simon et al. relate to a method and device used to insert an artificial meshwork in order to treat an eye with glaucoma and lower the intraocular pressure of the eye.
Needles and tissue cutting devices are known in the art and include U.S. Patent Application Publication No. 2012/0253228 to Schembre et al. and related U.S. Design Pat. No. D657461 to Schembre et al. which relate to a. biopsy needle tip and endoscopic ultrasound-guided biopsy needle. U.S. Pat. No. 4,874,375 to Ellison et al, relates to an improved tissue retractor particularly adapted for use during arthroscopic surgery. U.S. Pat. No. 5,718,237 to J R Haaga relates to a side cut needle including a solid stylet telescopically received within an inner tubular cannula which is telescopically received within an outer tubular cannula. U.S. Pat. Nos. 6,709,408, 6,872,185, and 6,890,309 to John Fisher describe a dual action biopsy needle that scrapes tissue of cellular thickness from a lesion during forward and rearward reciprocations of the needle along its longitudinal axis of symmetry. U.S. Patent Application Publication No. 2006/0052722 to Brautigam et al. describes a specimen retrieving needle having a closed lead end and with an outside diameter of less than 1.0 mm U.S. Patent Application Publication No. 2009/0287233 to J Huculak describes a small gauge mechanical tissue cutter/aspirator probe useful for removing the trabecular meshwork of a human eye.
Trabeculectomy has been the glaucoma surgery of choice since it was described for the first time in 1968 (Cairns J E, AM J OPHTHALMOL 66(4): 673-9 (1968)). Trabeculectomy is often augmented with topically applied anticancer drugs, such as 5-flurouracil or mitomycin-C to decrease scarring and increase the likelihood of surgical success.
Several studies have shown that trabeculectomy provides lower intraocular pressure (IOP) and reduces TOP daily fluctuation when compared with medical therapy (Wilensky J T et al., TRANS AM OPHTHALMOL SOC 92: 377-81 (1994); Lichter P R, et al., OPHTHALMOLOGY 108(11): 1943-53 (2001)). However, at least 20% of eyes with trabeculectomy will require glaucoma medication five years after surgery to maintain an adequate IOP control (Molteno A C et al., OPHTHALMOLOGY 106(9): 1742-50 (1999)).
For these reasons, surgeons have tried for decades to develop a workable surgery for the trabecular meshwork. The role of uveoescleral drainage, described first in 1965, has become an interesting and new approach to control IOP (A Bill, INVEST OPHTHALMOL 4(5): 911-9 (1965)). Studies have demonstrated a negative hydrostatic pressure from the anterior chamber to the suprachoroidal space (Jordan J F, et al., J GLAUCOMA 15(3): 200-5 (2006)). When the filtration bleb is flat or not obvious and the patient has a good IOP control, the participation of uveoescleral outflow may be larger (Ito K, et al., J GLAUCOMA 11(6): 540-2 (2002)).
Therefore, described herein is a new surgical device and surgical procedure that is faster, safer, and less expensive than currently available modalities.